1. Field of the Invention
The present invention relates to a wireless communication apparatus which is used, for example, in a cellular system.
2. Description of the Related Art
As is well known, in a mobile communication system such as a cellular system, the transmission power of a wireless communication apparatus is controlled. In general, the transmission power control aims at setting the reception quality at a desired value. In the transmission power control of a mobile wireless terminal apparatus in the cellular system, the reception quality in a base station apparatus is made to fall within a desired range.
The transmission power control is determined by a propagation loss (path loss), and noise (N)+interference (I). The measurement of the pass loss is executed by comparing transmission power and reception power. The transmission power is information which is possessed by a transmission side, and the reception power is control information which is possessed by a reception side. Thus, the exchange (signaling) of control information is necessary between the transmission side and the reception side
In a practically implemented cellular system (see, e.g. 3GPP TS 36.213 V8.2.0 (March 2008)), in the mobile wireless terminal apparatus, the measurement of path loss, which is used in the power control of an uplink for transmission to a base station apparatus, is executed, in some cases, on the basis of the transmission power of a downlink for transmission from the base station and the reception power in the mobile wireless terminal apparatus. Specifically, the base station apparatus reports transmission power to the mobile wireless terminal apparatus, and the mobile wireless terminal apparatus finds downlink reception power and measures downlink path loss on the basis of this reception power and the reported transmission power.
Exactly speaking, the downlink path loss and the uplink path loss are different. However, these are almost common with respect to the distance loss and shadowing loss. The downlink path loss can be measured by the mobile wireless terminal apparatus if the information relating to the transmission power is reported from the base station apparatus. Thus, in the uplink transmission power control, too, the downlink path loss is utilized as an element for determining the transmission power set value.
In the meantime, there has been developed a system wherein a plurality of frequency bands are allocated to a mobile wireless terminal apparatus, and these plural frequency bands are put together and practically used as a single system band (see, e.g. 3GPP IMT advanced Workshop REV-080058 Summary of LTE Advanced Requirements presented at the workshop (April 2008)). In this system, even discrete frequency bands can be used as a single system band and, therefore, the operation efficiency can be improved. However, in order to enable simultaneous transmission/reception in plural frequency bands, it is desirable to take a measure to prevent the apparatus structure from becoming too complex, although the apparatus structure tends to become complex in this case.
In addition, in the case where the discrete frequency bands are used as the single system band, as described above, the frequency for measuring path loss and the frequency band for executing transmission power control become different. In this case, since the measured path loss and the path loss of the object of transmission power control are different, there arises a problem that good transmission power control cannot be executed.